# Osmium tetroxide, as Os — US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side

For Osmium tetroxide, as Os, pel (ppm) is 0.0002; pel (mg/m³) is 0.002; stel (ppm) is 0.0006; stel (mg/m³) is 0.006, verified against its source on 2026-08-05.

- **Substance:** Osmium tetroxide, as Os
- **PEL (ppm):** 0.0002
- **PEL (mg/m³):** 0.002
- **STEL (ppm):** 0.0006
- **STEL (mg/m³):** 0.006

## What the source says

> 20816120 | | Osmium tetroxide, as Os | 0.0002 | 0.002 | | 0.0006 | 0.006

## Source

- https://www.dir.ca.gov/title8/5155.html

Last verified: 2026-08-05. Review by: 2027-08-05.
Part of [US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side](https://referencesource.org/workplace-exposure-limits/).